Field of the Invention
The invention relates to a resin identification device, particularly to a resin identification device using an infrared spectrophotometer (for example, a Fourier transform infrared spectrophotometer, hereinafter abbreviated as “FTIR”) for an identification section.
Description of the Related Art
A Michelson two-beam interferometer utilized for an FTIR has a configuration in which infrared light emitted from an infrared light source is divided by a beam splitter in two directions toward a stationary mirror and a movable mirror, and the infrared light reflected back from the stationary mirror and the infrared light reflected back from the movable mirror are combined by the beam splitter and sent along one optical path. At this moment, when the movable mirror is moved back and forth in an incident light axial direction, a difference in optical path length between the two light beams obtained by the division changes. Therefore, the combined light becomes interference light (interferogram) of which intensity changes according to the position of the movable mirror.
Such interference light is irradiated on a surface of a sample, and a wavelength of the light reflected by the surface of the sample is investigated using an infrared detector. Thereby, a component analysis of the sample is carried out.
FIG. 4 is a plan view illustrating a configuration of a conventional FTIR; FIG. 5 is a side view of the FTIR shown in FIG. 4. Moreover, a direction horizontal to the ground is referred to as direction X, a direction horizontal to the ground and perpendicular to the direction X is referred to as direction Y, and a direction perpendicular to both the directions X and Y is referred to as direction Z.
An FTIR 100 includes: an infrared light source section 110 that emits infrared light, an infrared light detection section 120, a sample arrangement section 130 where a sample S is arranged, and a control section 150.
The infrared light source section 110 includes: an infrared light source 12 that emits infrared light, a main interferometer principal part 40 that produces an interferogram, plane mirrors 13 and 14, and a parabolic mirror (condensing mirror) 111. The infrared light emitted from the infrared light source 12 is irradiated to a beam splitter 42 of the main interferometer principal part 40 via the plane mirrors 13 and 14.
In the main interferometer principal part 40, a movable mirror unit 41 including a movable mirror 41a, the beam splitter 42, and a stationary mirror unit 43 including a stationary mirror 43a are arranged. According to such a main interferometer principal part 40, the infrared light emitted from the infrared light source 12 is irradiated to the beam splitter 42 by which the infrared light is divided in two directions toward the movable mirror 41a and the stationary mirror 43a. Then, the infrared light reflected by the movable mirror 41a and the infrared light reflected by the stationary mirror 43a are returned to the beam splitter 42, combined by the beam splitter 42, and sent to the parabolic mirror 111 via the plane mirrors 13 and 14. At this moment, since the movable mirror 41a moves back and forth reciprocally in an incident light axial direction M, the difference in optical path length between the two light beams obtained by the division changes periodically, and the light heading from the beam splitter 42 to the parabolic mirror 111 becomes an interferogram in which an amplitude varies over time.
The infrared light detection section 120 includes: an infrared detector 21 that detects the interferogram (infrared light), and two parabolic mirrors (condensing mirrors) 122 and 23.
The sample arrangement section 130 is arranged in a position corresponding to a lower part of the FTIR 100. The sample arrangement section 130 has a platelike body. In a side view, the parabolic mirror 111 is provided in the upper left direction of the platelike body for reflecting light to the lower right direction, and the parabolic mirror 122 is provided in the upper right direction of the platelike body for reflecting the light from the lower left direction. Accordingly, as shown in FIG. 6A, when the sample S is placed in a position (measurement position) on an upper surface of the platelike body, the light collected by the parabolic mirror 111 is irradiated at a measurement point on an upper surface of the sample S, and the light reflected by the measurement point on the upper surface of the sample S is formed into parallel light by the parabolic mirror 122, such that the parallel light is collected to the infrared detector 21 by the parabolic mirror 23.
In addition, for reuse of a resin product (resin piece), it is necessary to identify the type of resin (e.g., polypropylene (PP), polystyrene (PS), or acrylonitrile butadiene styrene (ABS), etc.). A system that utilizes infrared spectroscopy to sequentially measure resin pieces so as to determine the type of resin has been manufactured and marketed (e.g., see Patent Document 1).
In one example thereof, the sample arrangement section 130 that is capable of sequentially arranging resin pieces S in predetermined positions includes: a disc-shaped table 134 that has a central part and a peripheral part, a driving mechanism (not illustrated) that rotates the disc-shaped table 134 with the central part of the disc-shaped table 134 as the axis of rotation, and a laser sensor (sample trigger function) 135 for detecting that the resin pieces S are in the predetermined positions. Moreover, data detected by the laser sensor 135 is sent to the control section 150.
According to such a sample arrangement section 130, after a plurality of resin pieces S (the first resin piece S1, the second resin piece S2, . . . ) are placed on the peripheral part of the disc-shaped table 134, the disc-shaped table 134 is rotated clockwise at a predetermined speed by the driving mechanism, thereby sequentially arranging the resin pieces S in the predetermined positions in a manner that the first resin piece S1 is arranged in its predetermined position when a predetermined time elapses after the laser sensor 135 has detected the first resin piece S1, then the second resin piece S2 is arranged in its predetermined position when a predetermined time elapses after the laser sensor 135 has detected the second resin piece S2, and so on.
The control section 150 includes: a light intensity information obtaining part that obtains light intensity information (reflected light intensity) from the infrared detector 21, an information obtaining part that obtains information regarding presence or absence of a sample from the laser sensor 135, and a sample measurement part that produces an absorption spectrum of the first resin piece S1 or an absorption spectrum of the second resin piece S2 based on the obtained light intensity information and information regarding presence or absence of the sample.